ANS-C01 Network Management and Operations Practice Question
A company is using AWS Direct Connect with a private VIF to access their VPC. Users report intermittent connectivity issues. You check the Direct Connect console and see that the virtual interface state is 'down'. What is the MOST likely cause?
⚠ Common exam trap
Test-takers frequently assume a VIF 'down' state is caused by physical or Layer 1 issues (like MACsec or jumbo frames), but the VIF state is directly tied to the BGP session status, not the underlying physical link.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
BGP session between the customer router and AWS is down.
A private VIF relies on a BGP session between the customer router and the AWS Direct Connect router to exchange routes and maintain the virtual interface state. When the BGP session goes down, the VIF state transitions to 'down' because no routing information is being exchanged, causing connectivity loss. This is the most direct and common cause of a VIF being in the 'down' state.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
AWS Site-to-Site VPN is not established.
Why it's wrong here
VPN is a separate connection and does not affect Direct Connect VIF state.
- ✗
MACsec encryption is misconfigured on the customer router.
Why it's wrong here
MACsec misconfiguration would affect encryption but not cause the VIF state to be down.
- ✓
BGP session between the customer router and AWS is down.
Why this is correct
A private VIF requires an active BGP session; if BGP is down, the VIF state becomes down.
- ✗
Jumbo frames are enabled on the VIF but not supported by the customer router.
Why it's wrong here
Jumbo frames do not affect the VIF state; they affect packet forwarding.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This ANS-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the ANS-C01 exam.